Microwave antenna assembly and method of using the same

ABSTRACT

A microwave antenna assembly comprising an elongate shaft having proximal and distal ends and a lumen defined therebetween, a conductive member at least partially disposed within the inner lumen of elongate shaft, conductive member being selectively deployable relative to a distal end of elongate shaft from a first condition wherein a distal end of conductive member at least partially abuts the distal end of elongate shaft to a second condition wherein the distal end of conductive member is spaced relative to the distal end of elongate shaft and a first dielectric material disposed between elongate shaft and conductive member, wherein a portion of conductive member is distal to the distal end of elongate shaft and adapted to penetrate tissue.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.13/281,605, filed Oct. 26, 2011, which is a divisional of U.S. patentapplication Ser. No. 11/529,823 which is now U.S. Pat. No. 8,068,921,filed Sep. 29, 2006, the entire contents of each of which areincorporated herein by reference.

BACKGROUND

1. Technical Field

The present disclosure relates generally to medical/surgical ablationassemblies and methods of their use. More particularly, the presentdisclosure relates to microwave antenna assemblies configured for directinsertion into tissue for diagnosis and treatment of the tissue andmethods of using the same.

2. Background of Related Art

In the treatment of diseases such as cancer, certain types of cancercells have been found to denature at elevated temperatures (which areslightly lower than temperatures normally injurious to healthy cells).These types of treatments, known generally as hyperthermia therapy,typically utilize electromagnetic radiation to heat diseased cells totemperatures above 41° C. while maintaining adjacent healthy cells atlower temperatures where irreversible cell destruction will not occur.Other procedures utilizing electromagnetic radiation to heat tissue alsoinclude ablation and coagulation of the tissue. Such microwave ablationprocedures, e.g., such as those performed for menorrhagia, are typicallydone to ablate and coagulate the targeted tissue to denature or kill it.Many procedures and types of devices utilizing electromagnetic radiationtherapy are known in the art. Such microwave therapy is typically usedin the treatment of tissue and organs such as the prostate, heart, andliver.

One non-invasive procedure generally involves the treatment of tissue(e.g., a tumor) underlying the skin via the use of microwave energy. Themicrowave energy is able to non-invasively penetrate the skin to reachthe underlying tissue. However, this non-invasive procedure may resultin the unwanted heating of healthy tissue. Thus, the non-invasive use ofmicrowave energy requires a great deal of control. This is partly why amore direct and precise method of applying microwave radiation has beensought.

Presently, there are several types of microwave probes in use, e.g.,monopole, dipole, and helical. One type is a monopole antenna probe,which consists of a single, elongated microwave conductor exposed at theend of the probe. The probe is sometimes surrounded by a dielectricsleeve. The second type of microwave probe commonly used is a dipoleantenna, which consists of a coaxial construction having an innerconductor and an outer conductor with a dielectric separating a portionof the inner conductor and a portion of the outer conductor. In themonopole and dipole antenna probe, microwave energy generally radiatesperpendicularly from the axis of the conductor.

SUMMARY

The present disclosure describes a device structurally robust for directinsertion into tissue, without the need for additional introducers orcatheters, while in a first condition, and device, in a secondcondition, forms a microwave antenna capable of producing a controllableand predictable heating pattern in a clearly defined area or volume ofablation.

The present disclosure relates generally to microwave antenna assembliesand methods of their use, e.g., in tissue ablation applications. Moreparticularly, the present disclosure relates to microwave antennaassemblies configured for direct insertion into tissue for diagnosis andtreatment of the tissue and methods of using the same.

A microwave antenna assembly of the present disclosure comprises anelongate shaft having proximal and distal ends and an inner lumendefined therebetween, a conductive member at least partially disposedwithin the inner lumen of elongate shaft, conductive member beingselectively deployable relative to a distal end of elongate shaft from afirst condition wherein a distal end of the conductive member at leastpartially abuts the distal end of elongate shaft to a second conditionwherein the distal end of conductive member is spaced relative to thedistal end of elongate shaft, and a first dielectric material disposedbetween elongate shaft and conductive member wherein a portion ofconductive member is distal to the distal end of elongate shaft andadapted to penetrate tissue.

In yet another embodiment of the present disclosure, microwave antennaassembly comprises an elongate shaft having a lumen defined therein, aconductive member partially disposed within the lumen of elongate shaftwherein conductive member including a geometry at a distal end thereofconfigured to penetrate tissue, a first dielectric material disposedbetween elongate shaft and at least a portion of conductive member and asecond dielectric material which covers at least a portion of conductivemember wherein at least one of elongate shaft, conductive member, firstdielectric material the second dielectric material being configured toselectively deploy relative to a distal end of an introducer from afirst condition wherein a distal end of conductive member at leastpartially abuts a distal end of introducer to a second condition whereinthe distal end of conductive member is spaced relative to the distal endof introducer.

In yet another embodiment of the present disclosure, a method fordeploying a microwave antenna assembly comprising the steps of advancinga microwave antenna assembly in a first condition to a region of tissueto be treated whereby a distal portion of microwave antenna assemblydefines a pathway through the tissue during penetration, deploying thedistal portion of microwave electrosurgical energy delivery apparatus toa second condition whereby the deployed distal portion of the microwaveantenna assembly biases to a predetermined configuration, treating theregion of tissue with electrosurgical energy, retracting the deployeddistal portion of microwave antenna assembly to the first condition andwithdrawing microwave antenna assembly from tissue.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a microwave antenna assembly accordingto an embodiment of the present disclosure shown in a first condition;

FIG. 2 is a perspective view of the microwave antenna assembly of FIG.1, shown in a second condition;

FIG. 3 is an exploded perspective view of the microwave antenna assemblyof FIGS. 1 and 2;

FIG. 4 is an enlarged perspective view of the indicated area of detailof FIG. 3;

FIG. 4A is a cross-sectional view as taken through 4A-4A of the biaseddistal portion of the conductive member of FIG. 4;

FIG. 5 is a schematic cross-sectional view of a distal portion of amicrowave antenna assembly according to another embodiment of thepresent disclosure, shown in a first condition;

FIG. 6 is a schematic cross-sectional view of the distal portion of themicrowave antenna assembly of FIG. 5, shown in a second condition;

FIG. 7 is an enlarged view of the indicated area of detail of FIG. 6;

FIG. 8 is a schematic cross-sectional view of a distal portion of amicrowave antenna assembly according to another embodiment of thepresent disclosure, shown in a first condition;

FIGS. 8A-8F illustrate alternate embodiments of distal portions ofconductive members of the microwave assemblies disclosed herein;

FIG. 9 is a schematic distal perspective view of a microwave antennaassembly according to a further embodiment of the present disclosure,shown in a first condition;

FIG. 10 is a longitudinal cross-sectional view of the distal portion ofthe microwave assembly of FIG. 9;

FIG. 11 is a longitudinal cross-sectional view of the distal portion ofthe microwave antenna assembly of FIGS. 9 and 10, shown in a secondcondition;

FIG. 12 is a longitudinal cross-sectional view of a distal portion of amicrowave antenna assembly according to an alternate embodiment of thepresent disclosure, shown in a first condition;

FIG. 13 is a longitudinal cross-sectional view of a distal portion of amicrowave antenna assembly according to an alternate embodiment of thepresent disclosure, shown in a first condition;

FIG. 14 is an elevational view of a portion of a conductive memberaccording to an embodiment of the present disclosure;

FIG. 15 is a schematic cross-sectional view of a microwave antennaassembly according to another embodiment of the present disclosure withthe conductive member of FIG. 14, shown partially deployed;

FIG. 16 is a plan view of a portion of the conductive member accordingto an embodiment of the present disclosure;

FIG. 17 is a schematic cross-sectional view of a microwave antennaassembly according to another embodiment of the present disclosure withthe conductive member of FIG. 16, shown partially deployed;

FIG. 18 is a side elevation view of a distal portion of a microwaveassembly according to a further embodiment of the present disclosure,shown in a first condition;

FIG. 19 is an enlarged longitudinal cross-section view of the distalportion of the microwave antenna assembly of FIG. 18.

FIG. 20 is a side elevational view of the microwave antenna assembly ofFIGS. 18 and 19, shown in a second condition;

FIG. 21 is an enlarged longitudinal cross-sectional view of theindicated area of detail of the microwave antenna assembly of FIG. 20;

FIG. 22 is a schematic perspective view of a microwave antenna assemblyaccording to yet another embodiment of the present disclosure, shown ina first condition;

FIG. 23 is an enlarged perspective view of the distal portion of themicrowave antenna assembly of FIG. 22; and

FIG. 24 is a perspective view of the microwave antenna assembly of FIG.22, shown in a second condition.

DETAILED DESCRIPTION

Embodiments of the presently disclosed microwave antenna assembly willnow be described in detail with reference to the drawing figures whereinlike reference numerals identify similar or identical elements. As usedherein and as is traditional, the term “distal” refers to the portionwhich is furthest from the user and the term “proximal” refers to theportion that is closest to the user. In addition, terms such as “above”,“below”, “forward”, “rearward”, etc. refer to the orientation of thefigures or the direction of components and are simply used forconvenience of description.

During invasive treatment of diseased areas of tissue in a patient theinsertion and placement of an electrosurgical energy delivery apparatus,such as a microwave antenna assembly, relative to the diseased area oftissue is critical for successful treatment. Generally, assembliesdescribed herein allow for direct insertion into tissue while in a firstcondition followed by deployment of the distal penetrating portionthereof to a second condition, thereby forming a microwave antenna atthe distal end of the assembly for delivery of microwave electrosurgicalenergy. An assembly that functions similarly may be found in U.S. PatentApplication Publication No. 2003/0195499 A1, filed Oct. 15, 2002, whichis herein incorporated by reference.

Referring now to FIGS. 1-7, a microwave antenna assembly, according toan embodiment of the present disclosure, is shown as 10. The microwaveantenna assembly 10 includes an introducer 16 having an elongate shaft12 and a conductive member 14 slidably disposed within elongate shaft12, a cooling assembly 20 having a cooling sheath 21, a cooling fluidsupply 22 and a cooling fluid return 24, and an electrosurgical energyconnector 26.

Connector 26 is configured to connect the assembly 10 to anelectrosurgical power generating source 27, e.g., a generator or sourceof radio frequency energy and/or microwave energy, and supplieselectrosurgical energy to the distal portion of the microwave antennaassembly 10. During initial insertion into tissue, while in the firstcondition, assembly 10 defines a path through the tissue by virtue ofthe mechanical geometry of the distal portion of the conductive member14 and, if needed, by the application of energy to tissue, e.g.electrical, mechanical or electro-mechanical energy.

As seen in FIGS. 1 and 2, microwave antenna assembly 10 includes a firstcondition in which conductive member 14 is in a first positionsubstantially entirely within elongate shaft 12 and at least one secondcondition in which conductive member 14 is at least at a second positionextended from elongate shaft 12. While in the first condition, a distalend or tip 14 a of conductive member 14 is positioned beyond a distalend 12 a of elongate shaft 12. While in the second condition, distal end14 a of conductive member 14 is spaced a distance relative to distal end12 a of elongate shaft 12. Second condition, as applied in the presentdisclosure, is any position, configuration or condition, wherein thedistal end 14 a of conductive member 14 is not in the first condition,e.g., distal end 14 a of conductive member 14 is spaced a distancerelative to distal end 12 a of elongate shaft 12. For example, asillustrated in FIG. 2, conductive member may be biased to asubstantially pre-determined configuration or, as illustrated in FIGS.14 and 16, a portion of the conductive member may be biased to apre-determined configuration. During deployment or retraction ofconductive member 14, between the first condition and the secondcondition, distal end 14 a of the conductive member 14 defines a paththrough the tissue by virtue of the mechanical geometry of the distalportion thereof and/or the application of energy to tissue, e.g.electrical, thermal mechanical or electro-mechanical energy.

Elongate shaft 12 and conductive member 14 are configured as a coaxialcable, in electro-mechanical communication with connector 26, which iscapable of delivering electrosurgical energy. Conductive member 14 iscapable of delivering radio frequency energy in either a bipolar ormonopolar mode. Radio frequency energy can be delivered while microwaveantenna assembly 10 is in the first or second condition. Deployment ofconductive member 14 to the second condition, as illustrated in FIG. 2,forms a microwave antenna “M” at the distal end of microwave antennaassembly 10 capable of delivering microwave energy to a target tissue.

Elongate shaft 12 may be formed from a flexible, semi-rigid or rigidmicrowave conductive cable with the original inner conductor removed andreplaced with conductive member 14. Elongate shaft 12 and conductivemember 14 may be formed of suitable conductive material including andnot limited to copper, gold, silver or other conductive metals havingsimilar conductivity values. Alternatively, elongate shaft 12 and/orconductive member 14 may be constructed from stainless steel or may beplated with other materials, e.g., other conductive materials, such asgold or silver, to improve their respective properties, e.g., to improveconductivity, decrease energy loss, etc.

As seen in FIGS. 2-4A, conductive member 14 includes a proximal portion32, a biased distal portion 34, and a distal tip portion 36. The variousportions 32, 34, 36 of conductive member 14 may be constructed of one ormore individual elements joined together or may be constructed from asingle monolithic element. Conductive member 14 may be constructed fromsuitable materials exhibiting good shape memory properties, such as, forexample, nitinol and stainless steel. Conductive member 14 may bepartially or fully plated with a suitable material, such as gold orsilver, in order to further increase the electrical conductivitythereof.

When microwave antenna assembly 10 is in the first condition, as shownin FIG. 1, at least a portion of distal tip portion 36 is disposeddistal of elongate shaft 12 and introducer 16 concomitantly therewith,proximal portion 32 and biased distal portion 34 of conductive member 14are partially disposed within inner lumen of elongate shaft 12 or innerlumen of introducer 16 and are capable of conducting radio frequencyenergy to distal tip portion 36. When microwave antenna assembly 10 isin the second condition, as shown in FIG. 2, proximal portion 32 ofconductive member 14 is partially disposed within the inner lumen ofelongate shaft 12 or the inner lumen of introducer 16. In the secondcondition, biased distal portion 34 and distal tip portion 36 ofconductive member 14 in conjunction with the distal end of the coaxialtransmission line (not shown) form a microwave antenna capable ofdelivering microwave energy to the target tissue. Proximal portion 32forms an inner conductor of a coaxial transmission line and elongateshaft 12 forms an outer conductor of the coaxial transmission line.Adjustments to the dimension and diameter of proximal portion 32 andelongate shaft 12, as well as the type of dielectric material used toseparate proximal portion 32 and elongate shaft 12, can be made tomaintain proper impedance.

When microwave antenna assembly 10 is in a retracted or first condition,as seen in FIG. 1, biased distal portion 34 is disposed within and/orconstrained by elongate shaft 12 or introducer 16. When microwaveantenna assembly 10 is in a deployed or second condition, as seen inFIG. 4, biased distal portion 34 deflects to a pre-determinedconfiguration. The pre-determined configuration may be one of a varietyof shapes so long as distal portion 34 substantially encloses a definedarea, i.e., the shape surrounds at least a portion or majority of thetarget tissue. Accordingly, when deployed or in the second condition,biased distal portion 34 deflects to a suitable pre-determinedconfiguration, such as, for example, circles, ellipses, spirals,helixes, squares, rectangles, triangles, etc., various other polygonalor smooth shapes, and partial forms of the various shapes so long as aportion or majority of the target tissue is surrounded.

The cross-sectional profile of biased distal portion 34 can be differentfrom the cross-sectional profile of the other portions of conductivemember 14. As seen in FIG. 4A, biased distal portion 34 of conductivemember 14 may have an oblong cross-sectional profile; however, othersuitable cross-sectional profiles, e.g. round, oval, square, etc. arecontemplated. The shape and dimension of distal portion 34 may influencethe microwave matching properties and the ability of the microwaveantenna to deliver energy. The cross-sectional profile in the distalportion 34 may vary along its length to suitably match the antenna tothe target tissue. Mechanically, different cross-sectional profiles mayaid in the deployment of microwave antenna assembly 10 as desired andmay aid in the ability of distal portion 34 to form the pre-determinedconfiguration.

Referring again to FIG. 4, distal tip portion 36 is positioned on biaseddistal portion 34 of conductive member 14. The geometry of distal tipportion 36 is configured to define a pathway through the tissue duringtissue penetration. The geometry of distal tip portion 36, will bediscussed in the various embodiments hereinbelow.

Relatively smooth transitions between the various portions of conductivemember 14 are made to avoid stress concentrators and to facilitatetissue penetration during insertion, deployment and retraction. As seenin FIG. 4, a transition 33 between proximal portion 32 and biased distalportion 34 is tapered in order to strengthen the transition and to avoidany stress points. Tapered transition 33 also aids in forming a returnpathway for conductive member 14 during retraction. Other methods mayalso be used to strengthen the joint if multiple pieces are used.

As seen in FIG. 3, a first dielectric 28 is preferably disposed betweenat least a portion of elongate shaft 12 and conductive member 14 toprovide insulation therebetween. First dielectric material 28 may besubstantially disposed on the proximal portion 32 of conductive member14 and may be slidably disposed within elongate shaft 12 or the positionof first dielectric 28 may be fixed relative to elongate shaft 12 withthe conductive member 14 slidably disposed with first dielectric 28.First dielectric material 28 may constitute any number of appropriatematerials, including air. The placement and configuration of firstdielectric material 28 relative to conductive member 14 is discussed inadditional embodiments hereinbelow.

With continued reference to FIGS. 1-3, cooling assembly 20 surroundselongate shaft 12 and forms a water-tight seal therewith. Coolingassembly 20 includes an elongate cooling sheath 21 configured toco-axially extend over elongate shaft 12, a cooling fluid supply 22fluidly connected to cooling sheath 21, and a cooling fluid return 24,fluidly connected to cooling sheath 21. In operation, as will bediscussed in greater detail below, cooling fluid enters cooling sheath21 though cooling fluid supply 22 and is delivered to a distal end ofcooling sheath 21 through one or more thin wall polyimide tubes (notexplicitly shown) disposed within an inner lumen of cooling sheath 21.Additionally, cooling fluid flows away from the distal end of coolingsheath 21 to a proximal end thereof, absorbs energy, and exits throughcooling fluid return 24.

As seen in FIGS. 1-3, handle 18 is configured to provide a grippingmechanism for the clinician, an interface for various controls andconnectors for the microwave antenna assembly 10. Handle 18 defines anaccess slot 19 that is configured to provide access to connector 26,cooling fluid supply 22 and cooling fluid return 24. A selector 29,positioned on the proximal end of handle 18, connects to theelectrosurgical energy delivery source 27. Selector 29 provides a meansfor the clinician to select the energy type, e.g., radio frequency ormicrowave, the energy delivery mode, e.g., bipolar, monopolar, and themode of operation, e.g., manual delivery or automatic delivery duringdeployment from a first to a second condition.

Introducer 16, secured to the distal end of handle 18, is slightlylarger than elongate shaft 12. The increased gauge size provides addedstrength and rigidity to the microwave antenna assembly for directinsertion into tissue. A distal portion of introducer 16 may be taperedto create a smooth transition between introducer 16 and adjacentcomponents of the microwave antenna assembly 10. At least a portion ofintroducer 16 may be in direct contact with elongate shaft 12.

Deployment of the microwave antenna assembly 10 from the firstcondition, as seen in FIG. 1, to a second condition, as seen in FIG. 2,is accomplished by repositioning a slidable portion of the microwaveantenna assembly 10 relative to a fixed portion of the microwave antennaassembly 10. In the embodiment in FIGS. 1 and 2, the slidable portionincludes conductive member 14, cooling assembly 20 and connector 26, andthe fixed portion includes the elongate shaft 12, introducer 16 andhandle 18.

In one embodiment, to deploy the microwave antenna assembly 10 from thefirst condition to the second condition, a clinician grasps a portion ofthe fixed portion, for example, the handle, and repositions or slidesthe slidable portion distally until deployed to the second condition.Similarly, the clinician retracts the microwave antenna assembly 10 fromthe second condition to the first condition by grasping the fixedportion and repositioning or sliding the slidable portion proximallyuntil retracted to the second condition.

Handle 18 may maintain the position of the slidable portion relative tointroducer 16 and/or elongate shaft 12. As seen in FIGS. 1 and 2,cooling fluid supply 22 and cooling fluid return 24 may be restrained bythe access slot 19, formed in the handle 18, thereby limiting lateralmovement of the slidable portion during deployment and retraction. Guideslots (not shown), in the cooling fluid supply 22 and cooling fluidreturn 24, may provide a track adjacent access slot 19 that furtherrestricts lateral movement of the slidable portion and the fixed portionduring deployment and retraction. Various other suitable may be used forensuring alignment between the slidable portion and the fixed portion.

Microwave antenna assembly may include a motorized means for controllingthe position of the slidable portion. Motorized means mechanicallyengages at least a portion of the slidable portion and drives theslidable portion distally to deploy and proximally to retract. Deliveryof radio frequency energy during deployment may coincide with positionchange of the slidable portion by the motorized means.

Returning to FIG. 1-2, an embodiment of the microwave antenna assembly10 may include a position determining means 31, such as a suitablesensor, for determining the position of distal tip portion 36 ofconductive member 14. Position determining means 31 may includemechanical, magnetic, electrical or electro-mechanical means to providefeedback indicative of the position of distal tip portion 36.Positioning determining means 31 may mechanical engage a portion of aslidable portion or may electrically sense movement of the slidableportion relative to the positioning determining means 31. Alternatively,electrosurgical power generating source 27 may include electricalelements or circuitry configured to determine the presence of resistive,capacitive and/or inductive contact between conductive member 14 andelongate shaft 12 or introducer 16, indicating deployment of conductivemember 14 in a second condition.

In yet another embodiment of the present invention, position determiningmeans 31 and motorized means for positioning the slidable portion may becombined into a single device such as a micro-servo drive or similarmotorized means with position control.

Other more sophisticated means may be employed for determining theposition of the slidable portion, such as measuring the reflected power,or S₁₁, on either conductive member 14 or elongate shaft 12.Alternatively, the reflective power between conductive member 14 andelongate shaft 12, or S₁₂, could also be measured. The approximateposition of conductive member 14 relative to elongate shaft 12 may bedetermined by various reflective power signatures or profiles. Powersignatures and profiles may be specific for each microwave antennaassembly.

In yet another embodiment of the present disclosure, the position ofconductive member 14 is used to determine which type of energy thegenerator may supply. Radio frequency energy, delivered in either amonopolar or bipolar mode, is typically delivered while microwaveantenna assembly 10 is in a first condition (i.e., during positioning ofthe microwave antenna assembly 10 in tissue) and when deployed orretracted between the first condition and the second condition. Radiofrequency energy may be selectively supplied, in a bipolar mode, whenmicrowave antenna assembly 10 is in the first condition and, in amonopolar mode, when deploying or retracting conductive member betweenthe first condition and the second condition. Microwave energy may bedelivered by microwave antenna “M” following formation of the microwaveantenna “M” at the distal end of microwave antenna assembly 10.

Turning now to FIGS. 5-7, another embodiment of a microwave antennaassembly in accordance with the present disclosure is designated as 100.Microwave antenna assembly 100 is substantially similar to microwaveantenna assembly 10 and thus will only be described herein to the extentnecessary to identify differences in construction and operation.Microwave antenna assembly 100 includes an elongate shaft 112 or outerconductor, a conductive member, or inner conductor 114, and a firstdielectric material 128 interposed therebetween.

As depicted in FIG. 5, when microwave antenna assembly 100 is in a firstcondition first dielectric material 128 is disposed between elongateshaft 112 and conductive member 114. First dielectric material 128 andconductive member 114 are at least partially disposed within the lumenof elongate shaft 112. In the illustrated embodiment, a distal tipportion 136 of conductive member 114 is configured to penetrate tissue,and a distal tip portion of elongate shaft 112 is configured to notpenetrate tissue (e.g., the distal tip portion of elongate shaft 112 mayhave a blunt or rounded profile to prevent it from penetrating tissue).When microwave antenna assembly 100 is in the first condition, distaltip portion 136 abuts the distal end of elongate shaft 112 with at leasta portion of distal tip portion 136 extending distally beyond elongateshaft 112. A proximal section or surface of distal tip portion 136 is ofsimilar size and cross section as a distal portion of elongate shaft 112such that when in the first condition a smooth transition exists betweendistal tip portion 136 and elongate shaft 112. Distal tip portion 136may engage first dielectric material 128 or the distal end of elongateshaft 112; however, the geometry (i.e., size and/or shape) of distal tipportion 136 impedes retraction of distal tip portion 136 into elongateshaft 112.

As depicted in FIG. 6, conductive member 114 is deployed from orextended from first dielectric material 128 when microwave antennaassembly 100 is in a second condition. In the second condition, distaltip portion 136 is spaced relative to the distal end of elongate shaft112 and biased distal portion 134 of conductive member 114 is biased,flexed or bent to a pre-determined configuration.

As seen in FIG. 7, deployment of microwave antenna assembly 100 to thesecond condition places distal tip portion 136 in close proximity to theouter periphery or surface of elongate shaft 112 wherein resistive,capacitive and/or inductive contact exists between elongate shaft 112and distal tip portion 136 or biased distal portion 134 of conductivemember 114 and elongate shaft 112. It is desirable for the resistive,capacitive and/or inductive contact to be sufficient such that thecontact improves the efficiency of the energy delivery, i.e. lowerreflective power.

Resistive, capacitive and/or inductive contact between distal tipportion 136 and elongate shaft 112 improves the efficiency of energydelivery, i.e. lower reflective power. Microwave antenna assembly 100may include a shorting-wire that connects distal portion of conductivemember 114 to the distal portion of elongate shaft 112. Theshorting-wire may attach to and run along distal portion 134 of theconductive member 114, deploy with the conductive member 114 to a secondcondition and provide the desired short-circuit between distal tipportion 136 and elongate shaft 112. Conductive member 114 may be hollowand the shorting-wire may be housed therewithin.

In the embodiment illustrated in FIG. 8, microwave antenna assembly 100includes a cooling sheath 120 at least partially co-axially surroundingand extending over elongate member 112. Cooling sheath 120 may be formedof a conductive material, such as thin wall stainless steel. Elongatemember 112 and cooling sheath 120 are connected to one another in acontact area 140 wherein cooling sheath 120 and elongate member 112 areshorted. Contact area 140 creates a fluid-tight seal between a coolingchamber 142 and an outside surface 144 of microwave antenna assembly100. As seen in FIG. 8, a distal end of cooling sheath 120 is positioneddistally of a distal end of elongate shaft 112. Cooling sheath 120 may,in some embodiments, only partially surround elongate member 112. In anembodiment, the distal end of elongate shaft 112 may extend past thedistal end of cooling sheath 120 and engage tip portion 136 ofconductive member 114. The engagement of distal tip portion 136 toconductive member and/or elongate member 112 may be used to signifynon-deployment of the ring.

Referring now to FIGS. 3 and 8, cooling fluid supply 22 of coolingassembly 20, located on the proximal end of cooling sheath 21, maysupply cooling fluid to distal end of cooling chamber 142. Cooling fluidmay flow through cooling chamber 142 to cooling fluid return 24, locatedon proximal end of cooling sheath 21.

Microwave antenna assembly may include one or more temperature measuringdevice (not shown) such as a resistive temperature device (RTD) or athermocouple. The temperature measuring device may measure one or moreof the following: the temperature of the cooling fluid at one or morelocations within cooling chamber 142; the temperature of one or more ofthe components of the microwave antenna assembly; or the temperature ofpatient tissue.

With continued reference to FIG. 8, when microwave antenna assembly 100is in the first condition, distal tip portion 136 of conductive member114 engages the distal portion of cooling sheath 120 and/or the distalportion of elongate shaft 112 or a portion of first dielectric materialthat extends beyond cooling sheath 120 and elongate shaft 112 (ifcooling sheath 120 does not extend beyond distal end of elongate shaft112). Irrespective of which element distal tip portion 136 engages, asmooth transition is formed between an exterior surface of distal tipportion 136 and the adjacent abutting member in order to facilitatetissue penetration.

As mentioned above the distal tip portion is configured to define apathway through the tissue during tissue penetration and may have anysuitable geometry. Referring now to FIGS. 8A-8F, various geometries fordistal tip portions, used to define a pathway through the tissue, areillustrated as 150-155, respectively. FIGS. 8A and 8B depict geometriesof distal tip portion 150, 151, respectively, with smooth surfacesadapted to create a pathway through the tissue with the application ofelectrical energy, e.g., tear drop (FIG. 8A), hemispherical (FIG. 8B).FIGS. 8C and 8D depict geometries with sharp or piercing distal tipsadapted to create a pathway when applied with mechanical force. Othergeometries are suitable provided the distal edge of the distal tipportion forms a sharp feature as the leading edge for introducing thedevice to the desired location. If the pathway is created with theapplication of electrical and mechanical energy any of the geometriesillustrated in FIGS. 8A-8F, as well as other geometries, may beutilized. The distal portion of the first dielectric material 128 isadapted to conform to the geometry of the proximal surface of the distaltip portion 150, 151, 152, 153, 154, 155 depicted in FIGS. 8-8F,respectively.

Turning now to FIGS. 9-11, a microwave antenna assembly according toanother embodiment of the present disclosure is shown as 200. Microwaveantenna assembly 200 includes a transition member 260 disposed at thedistal end of elongate shaft 212 and at least partially surroundingconductive member 214. Transition member 260 includes a distal taperedsurface 260 that creates a smooth transition with elongate shaft 212 tofacilitate tissue penetration. As seen in FIG. 10, transition member 260is secured to the distal end of elongate shaft 212 by cooling sheath 220extending at least partially over elongate shaft 212 and transitionmember 260.

Transition member 260 strengthens the distal portion of the microwaveantenna assembly 200 for tissue penetration and acts as a dielectricelectrically insulating distal tip portion 236 from cooling sheath 220and elongate shaft 212. Transition member 260 also allows the maximumcross sectional area of the distal tip portion 236 to be reduced to avalue less than the cross sectional area of elongate shaft 212 or ofcooling sheath 220. The reduced maximum cross-sectional area of thedistal tip portion 236 creates a smaller pathway in tissue and requiresless force to penetrate tissue when deploying between a first conditionand a second condition.

With reference to FIG. 12, transition member 260 of microwave antennaassembly 200 engages both elongate shaft 212 and cooling sheath 220. Apress fit engagement is utilized to mate transition member 260 tocooling sheath 220 while a threaded engagement is used to matetransition member 260 to elongate shaft 212.

With reference to FIG. 13, cooling sheath 220 has been removed andtransition member 260 is mated with elongate shaft 212 via a threadedengagement, although other securing means and methods can be used.Distal tip portion 236, elongate shaft 212 and transition member 260create a smooth transition between one another in order to facilitatetissue penetration while microwave antenna assembly 200 is in a firstcondition. Various other suitable methods may be used for matingelements to one another.

Referring now to FIGS. 14 and 15, as described above conductive member114 includes a proximal portion 132, a biased distal portion 134 and adistal tip portion 136. When microwave antenna assembly 100 issubstantially in a first condition, as seen in FIG. 14, biased distalportion 134 and proximal portion 132 are substantially retracted withinelongate shaft 112 and are surrounded by first dielectric material 128while distal tip portion 136 is located distal of elongate shaft 112.When microwave antenna assembly 100 is in a second condition, as seen inFIG. 15, the portion of conductive member 114 exposed to tissue includesbiased distal portion 134 and distal tip portion 136. If radio frequencyenergy is utilized to define a pathway during deployment or retraction,distal portion 134 and distal tip portion 136 deliver radio frequencyenergy to tissue. While the main pathway will be created by thecurvilinear movement of distal tip portion 136 through tissue, lateralmovement of the deployed portion is possible since the entire deployedportion is energized with radio frequency energy.

Referring now to FIGS. 16 and 17, microwave antenna assembly 100includes a second dielectric material 162 disposed between elongateshaft 112 and conductive member 114. Second dielectric material 162covers at least a portion of conductive member 114 including asubstantial amount of the length of biased distal portion 134. Seconddielectric material 162 may be a PTFE shrink with a non-stick outersurface having a high temperature profile, although other suitabledielectrics may be used. The various properties of second dielectricmaterial 162, such as material type and thickness, can be adjusted tobetter match the antenna assembly to tissue. Second dielectric material162 defines the outer diameter of biased distal portion 134 ofconductive member 114. In one embodiment, the outer diameter of seconddielectric material 162 should form a smooth transition with theproximal end of distal tip portion 136 to facilitate movement ofconductive member in tissue between a first condition and a secondcondition. The outer diameter of the second dielectric material 162 isalso dimensioned to conform with the inner diameter of elongate shaft112 such that when microwave antenna assembly 100 is in a firstcondition biased distal portion 134 and second dielectric material 162are retracted within the lumen of elongate shaft 112.

As seen in FIG. 17, when microwave antenna assembly 100 is in a secondcondition, the portion of conductive member 114 deployed from microwaveantenna assembly 100 includes distal tip portion 136, biased distalportion 134 and second dielectric material 162 covering biased distalportion 134. If radio frequency energy is utilized, when deployingconductive member between a first condition and a second condition,distal tip portion 136 will deliver radio frequency energy to tissue.The pathway through the tissue is created by the curvilinear movement ofthe distal tip portion 136 through the tissue and the energy deliveredis concentrated at the distal end of distal tip portion 136.

The outer surface of second dielectric material 162 may also be coated.The coating is a suitable lubricious substance to aid in the movement ofconductive member 114 between a first condition and a second conditionas well as to aid in preventing tissue from sticking to the outersurface thereof. The coating itself may be made from suitableconventional materials, e.g., polymers, etc.

Yet another embodiment of a microwave antenna assembly 300, inaccordance with the present disclosure, is illustrated in FIGS. 18-22.In the present embodiment, microwave antenna assembly 300 includes anintroducer 316, a conductive member 314 and an elongate shaft 312slidably disposed within introducer 316, a first dielectric material 328interposed between conductive member 314 and elongate shaft 312, asecond dielectric material 362 interposed between conductive member 314and introducer 316 at a location distal of first dielectric material328, and a cooling sheath 320. Conductive member 314 includes a distaltip portion 336 configured to engage the distal portion of introducer316 and has a geometry such that distal tip portion 336 impedesretraction thereof into a lumen 316 a of introducer 316. Seconddielectric material 362 substantially covers biased distal portion 334of conductive member 314. The elongate shaft 312, cooling sheath 320 andfirst dielectric material 328 are positioned within lumen 316 a ofintroducer 316. It is envisioned that first dielectric material 362 andsecond dielectric material 328 may be the same or may be formed of thesame material.

As seen in FIGS. 18 and 19, distal tip portion 336 of conductive member314 forms a smooth transition with introducer 316 such that the distalend of the microwave antenna assembly 300 is adapted for penetratingtissue and to facilitate insertion of microwave antenna assembly 300into tissue.

As seen in FIGS. 20 and 21, microwave antenna assembly 300 has beendeployed to a second condition. When microwave antenna assembly 300 isdeployed to the second condition, elongate shaft 312, cooling sheath 320and first dielectric material 328 are repositioned and/or advanced froma proximal end portion of introducer 316 to a distal end portion ofintroducer 316. In particular, elongate shaft 312 is advanced an amountsufficient to contact the distal end portion of introducer 316 at ornear a distal tip 364 thereof to form a resistive, capacitive and/orinductive connection therebetween. As discussed in the earlierembodiments, elongate shaft 312 contacts cooling sheath 320 and forms aresistive, capacitive and/or inductive connection at a contact area 340.When microwave antenna assembly 300 is in the second condition distalend of conductive member 314 is spaced a distance relative to a distalend of introducer 316 and bends around such that distal tip portion 336is in close proximity to an exterior surface of introducer 316. Distaltip portion 336 of conductive member 314 may have or be in resistive,capacitive and/or inductive contact with introducer 316.

In another embodiment of the present disclosure, cooling sheath 320 maybe incorporated into introducer 316 and conductive member 314, elongateshaft 312 and first and second dielectric materials 328, 362 areslidably positioned therewithin.

Another embodiment of microwave antenna assembly 400, in accordance withthe present disclosure, is illustrated in FIGS. 22-24. In the presentembodiment, microwave antenna assembly 400 includes a conductive member414, a first dielectric material 428 covering at least a portion of aproximal portion 432 of conductive member 414, a second dielectricmaterial 462 covering a biased distal portion 434 of conductive member414, and a connector 426 connected to the proximal end of conductivemember 414. A distal tip portion 436 of conductive member 414 isconfigured to engage a distal end of elongate shaft 412.

Microwave antenna assembly 400 further includes a cooling sheath 420extending over elongate shaft 412 and engaging elongate shaft 412 atcontact area 440. Cooling sheath 420 engages elongate shaft 412 in sucha manner so as to form a water-tight seal therebetween. Cooling fluid,supplied to the proximal end of a cooling chamber, defined betweencooling sheath 420 and elongate shaft 412, through a cooling fluidsupply 422, flows from the proximal end of the cooling chamber to thedistal end and returns through the cooling chamber to exit microwaveantenna assembly 400 through a cooling fluid return 424.

As seen in FIG. 23, when microwave antenna assembly 400 is in a firstcondition, distal tip portion 436 forms a smooth transition withelongate shaft 412 to facilitate tissue penetration. The geometry ofdistal tip portion 436 is such that retraction of distal tip portion 436into elongate shaft 412 is prevented. Elongate shaft 412 may also form asmooth transition with cooling sheath 420.

As seen in FIG. 24, when microwave antenna assembly 400 is in a secondcondition, distal tip portion 436 of conductive member 414 is spaced arelative distance to the distal end of elongate shaft 412, proximalportion 432 is substantially disposed within the lumen of elongate shaft412, and distal biased portion 434, covered by second dielectricmaterial 462, projects out from the distal end of elongate shaft 412.When distal tip portion 436 and distal biased portion 434 are deployedto the second condition a microwave antenna is formed. The distal end ofconductive member 414 may form a resistive, capacitive and/or inductiveconnection with elongate shaft 412, as discussed supra.

The applications of the microwave antenna assemblies and methods ofusing the assemblies discussed above are not limited to microwaveantennas used for hyperthermic, ablation, and coagulation treatments butmay include any number of further microwave antenna applications.Modification of the above-described assemblies and methods for using thesame, and variations of aspects of the disclosure that are obvious tothose of skill in the art are intended to be within the scope of theclaims.

1-16. (canceled)
 17. A method for deploying a microwave antennaassembly, comprising: advancing a microwave antenna assembly into tissuewith a conductive member of the microwave antenna assembly being in afirst configuration; deploying a distal portion of the conductivemember, the distal portion biasing the conductive member into apredetermined second configuration; delivering electrosurgical energythrough the conductive member to tissue; retracting the distal portionof the conductive member thereby returning the conductive member intothe first configuration.
 18. The method of claim 17, wherein advancingthe microwave antenna assembly includes delivering electrosurgicalenergy to tissue during the advancement.
 19. The method of claim 17,wherein deploying the conductive member includes deliveringelectrosurgical energy to tissue during the deployment.
 20. The methodof claim 17, wherein retracting the distal portion of the conductivemember includes delivering electrosurgical energy to tissue during theretraction.
 21. The method of claim 17, wherein deploying the distalportion of the conductive member includes: inserting the microwaveantenna assembly into an introducer; and inserting the introducer intotissue.
 22. The method of claim 21, wherein deploying the distal portionof the conductive member includes deploying the distal portion of theconductive member relative to a distal portion of an introducer intotissue.
 23. The method of claim 22, wherein advancing the microwaveantenna assembly into tissue includes advancing an elongated shaft ofthe microwave antenna assembly into tissue, the elongated shaft defininga lumen configured to receive the conductive member therein, a firstdielectric material disposed between the elongate shaft and at least aportion of the conductive member, and a second dielectric materialdisposed on at least a portion of the conductive member.
 24. The methodof claim 23, wherein deploying the distal portion of the conductivemember includes deploying at least one of the elongate shaft, theconductive member, the first dielectric material, or the seconddielectric material relative to the distal portion of the introducer.25. The method of claim 23, wherein the distal portion of the conductivemember has a diameter larger than a diameter of at least one of a distalportion of the introducer or a distal portion of the lumen of theelongated shaft.
 26. The method of claim 17, wherein deliveringelectrosurgical energy includes delivering radio frequency energy totissue with the conductive member in the first configuration.
 27. Themethod of claim 17, wherein delivering electrosurgical energy includesdelivering microwave energy to tissue with the conductive member in thesecond configuration.
 28. The method of claim 17, further comprising,determining the relative position of the conductive member via at leastone sensor.
 29. The method of claim 17, further comprising, cooling atleast a portion of the conductive member by contacting the conductivemember with a cooling sheath, the cooling sheath partially surroundingat least a portion of the conductive member and coupled to a coolantsource.